Most of the dialogs look fine now wrt HiDPI, but the Insert - Hyperlink is a notable ugly exception.
The relevant file is cuihyperdlg.cxx: http://opengrok.libreoffice.org/xref/core/cui/source/dialogs/cuihyperdlg.cxx
It needs some of the same fixes that have gone into other places: http://cgit.freedesktop.org/libreoffice/core/commit/?id=7347482cc360ad3dc9ed77047441c2e30476fed3
I believe this is an easy hack.
Migrating Whiteboard tags to Keywords: (EasyHack DifficultyInteresting SkillCpp TopicUI)
JanI is default CC for Easy Hacks (Add Jan; remove LibreOffice Dev List from CC)
Chirag Manwani committed a patch related to this issue.
It has been pushed to "master":
tdf#90795 Fix Hyperlink Dialog for HiDPI
It will be available in 5.2.0.
The patch should be included in the daily builds available at
http://dev-builds.libreoffice.org/daily/ in the next 24-48 hours. More
information about daily builds can be found at:
Affected users are encouraged to test the fix and report feedback.